| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <c62985530903020939o14b8d6b9o6646d6d7b401df07@mail.gmail.com>
Date: Mon, 2 Mar 2009 18:39:01 +0100
From: Frédéric Weisbecker <fweisbec@...il.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Ingo Molnar <mingo@...e.hu>,
Andrew Morton <akpm@...ux-foundation.org>,
Lai Jiangshan <laijs@...fujitsu.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Peter Zijlstra <peterz@...radead.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] ftrace: infrastructure for supporting binary record
2009/3/2 Steven Rostedt <rostedt@...dmis.org>:
>
>
> On Sat, 28 Feb 2009, Frederic Weisbecker wrote:
>
>> From: Lai Jiangshan <laijs@...fujitsu.com>
>>
>> Impact: save on memory for tracing
>>
>> Current tracers are typically using a struct(like struct ftrace_entry,
>> struct ctx_switch_entry, struct special_entr etc...)to record a binary
>> event. These structs can only record a their own kind of events.
>> A new kind of tracer need a new struct and a lot of code too handle it.
>>
>> So we need a generic binary record for events. This infrastructure
>> is for this purpose.
>>
>> [fweisbec@...il.com: rebase against latest -tip]
>>
>> Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com>
>> Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
>> ---
>> include/linux/ftrace.h | 3 +
>> kernel/trace/Kconfig | 6 +++
>> kernel/trace/Makefile | 1 +
>> kernel/trace/trace.c | 55 ++++++++++++++++++++++++++
>> kernel/trace/trace.h | 12 ++++++
>> kernel/trace/trace_bprintk.c | 87 ++++++++++++++++++++++++++++++++++++++++++
>> kernel/trace/trace_output.c | 76 ++++++++++++++++++++++++++++++++++++
>> 7 files changed, 240 insertions(+), 0 deletions(-)
>>
>> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
>> index 847bb3c..8ac2fac 100644
>> --- a/include/linux/ftrace.h
>> +++ b/include/linux/ftrace.h
>> @@ -222,6 +222,9 @@ extern int ftrace_make_nop(struct module *mod,
>> */
>> extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr);
>>
>> +#ifdef CONFIG_TRACE_BPRINTK
>> +extern int trace_vbprintk(unsigned long ip, const char *fmt, va_list args);
>> +#endif
>>
>> /* May be defined in arch */
>> extern int ftrace_arch_read_dyn_info(char *buf, int size);
>> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
>> index 02bc5d6..2e84fc7 100644
>> --- a/kernel/trace/Kconfig
>> +++ b/kernel/trace/Kconfig
>> @@ -86,6 +86,12 @@ config FUNCTION_GRAPH_TRACER
>> This is done by setting the current return address on the current
>> task structure into a stack of calls.
>>
>> +config TRACE_BPRINTK
>> + bool "Binary printk for tracing"
>> + default y
>> + depends on TRACING
>> + select BINARY_PRINTF
>> +
>> config IRQSOFF_TRACER
>> bool "Interrupts-off Latency Tracer"
>> default n
>> diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
>> index c931fe0..dba6157 100644
>> --- a/kernel/trace/Makefile
>> +++ b/kernel/trace/Makefile
>> @@ -22,6 +22,7 @@ obj-$(CONFIG_TRACING) += trace.o
>> obj-$(CONFIG_TRACING) += trace_clock.o
>> obj-$(CONFIG_TRACING) += trace_output.o
>> obj-$(CONFIG_TRACING) += trace_stat.o
>> +obj-$(CONFIG_TRACE_BPRINTK) += trace_bprintk.o
>> obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
>> obj-$(CONFIG_SYSPROF_TRACER) += trace_sysprof.o
>> obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o
>> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
>> index c5e39cd..3a3ae19 100644
>> --- a/kernel/trace/trace.c
>> +++ b/kernel/trace/trace.c
>> @@ -3572,6 +3572,61 @@ int __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap)
>> }
>> EXPORT_SYMBOL_GPL(__ftrace_vprintk);
>>
>> +/**
>> + * trace_vbprintk - write binary msg to tracing buffer
>> + *
>> + * Caller must insure @fmt are valid when msg is in tracing buffer.
>> + */
>> +int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
>> +{
>> + static DEFINE_SPINLOCK(trace_buf_lock);
>> + static u32 trace_buf[TRACE_BUF_SIZE];
>> +
>> + struct ring_buffer_event *event;
>> + struct trace_array *tr = &global_trace;
>> + struct trace_array_cpu *data;
>> + struct bprintk_entry *entry;
>> + unsigned long flags;
>> + int cpu, len = 0, size, pc;
>> +
>> + if (tracing_disabled || !trace_bprintk_enable)
>> + return 0;
>> +
>
> If this is called in the scheduler (we might want a ftrace_printk there),
> then the preempt_enable might cause a recursive crash.
>
> If a ftrace_printk is in schedule() but before we clear NEED_RESCHED, the
> preempt_enable below will cause schedule to be called again. Then we would
> again execute this trace and call schedule again, over and over till we
> corrupt the stack and crash the system.
Oh, right!
> That is what ftrace_preempt_disable() is for.
>
> It's defined in kernel/trace/trace.h:
>
> The way you use it is:
>
> int resched;
> [...]
>
> resched = ftrace_preempt_disable();
> [...]
>
> ftrace_preempt_enable(resched);
>
> This will safely disable preemption and enable it correctly.
>
Ok, will fix it.
>> + pc = preempt_count();
>> + preempt_disable_notrace();
>> + cpu = raw_smp_processor_id();
>> + data = tr->data[cpu];
>> +
>> + if (unlikely(atomic_read(&data->disabled)))
>> + goto out;
>> +
>> + spin_lock_irqsave(&trace_buf_lock, flags);
>> + len = vbin_printf(trace_buf, TRACE_BUF_SIZE, fmt, args);
>> +
>> + if (len > TRACE_BUF_SIZE || len < 0)
>> + goto out_unlock;
>> +
>> + size = sizeof(*entry) + sizeof(u32) * len;
>> + event = trace_buffer_lock_reserve(tr, TRACE_BPRINTK, size, flags, pc);
>> + if (!event)
>> + goto out_unlock;
>> + entry = ring_buffer_event_data(event);
>> + entry->ip = ip;
>> + entry->fmt = fmt;
>> +
>> + memcpy(entry->buf, trace_buf, sizeof(u32) * len);
>> + ring_buffer_unlock_commit(tr->buffer, event);
>> +
>> +out_unlock:
>> + spin_unlock_irqrestore(&trace_buf_lock, flags);
>> +
>> +out:
>> + preempt_enable_notrace();
>> +
>> + return len;
>> +}
>> +EXPORT_SYMBOL_GPL(trace_vbprintk);
>> +
>> static int trace_panic_handler(struct notifier_block *this,
>> unsigned long event, void *unused)
>> {
>> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
>> index f6fa0b9..92703b1 100644
>> --- a/kernel/trace/trace.h
>> +++ b/kernel/trace/trace.h
>> @@ -20,6 +20,7 @@ enum trace_type {
>> TRACE_WAKE,
>> TRACE_STACK,
>> TRACE_PRINT,
>> + TRACE_BPRINTK,
>> TRACE_SPECIAL,
>> TRACE_MMIO_RW,
>> TRACE_MMIO_MAP,
>> @@ -124,6 +125,16 @@ struct print_entry {
>> char buf[];
>> };
>>
>> +struct bprintk_entry {
>> + struct trace_entry ent;
>> + unsigned long ip;
>> + const char *fmt;
>> + u32 buf[];
>> +};
>> +#ifdef CONFIG_TRACE_BPRINTK
>> +extern int trace_bprintk_enable;
>> +#endif
>> +
>> #define TRACE_OLD_SIZE 88
>>
>> struct trace_field_cont {
>> @@ -284,6 +295,7 @@ extern void __ftrace_bad_type(void);
>> IF_ASSIGN(var, ent, struct stack_entry, TRACE_STACK); \
>> IF_ASSIGN(var, ent, struct userstack_entry, TRACE_USER_STACK);\
>> IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT); \
>> + IF_ASSIGN(var, ent, struct bprintk_entry, TRACE_BPRINTK);\
>> IF_ASSIGN(var, ent, struct special_entry, 0); \
>> IF_ASSIGN(var, ent, struct trace_mmiotrace_rw, \
>> TRACE_MMIO_RW); \
>> diff --git a/kernel/trace/trace_bprintk.c b/kernel/trace/trace_bprintk.c
>> new file mode 100644
>> index 0000000..1f8e532
>> --- /dev/null
>> +++ b/kernel/trace/trace_bprintk.c
>> @@ -0,0 +1,87 @@
>> +/*
>> + * trace binary printk
>> + *
>> + * Copyright (C) 2008 Lai Jiangshan <laijs@...fujitsu.com>
>> + *
>> + */
>> +#include <linux/kernel.h>
>> +#include <linux/ftrace.h>
>> +#include <linux/string.h>
>> +#include <linux/ctype.h>
>> +#include <linux/list.h>
>> +#include <linux/mutex.h>
>> +#include <linux/slab.h>
>> +#include <linux/module.h>
>> +#include <linux/seq_file.h>
>> +#include <linux/fs.h>
>> +#include <linux/marker.h>
>> +#include <linux/uaccess.h>
>> +
>> +#include "trace.h"
>> +
>> +/* binary printk basic */
>> +static DEFINE_MUTEX(btrace_mutex);
>> +static int btrace_metadata_count;
>> +
>> +static inline void lock_btrace(void)
>> +{
>> + mutex_lock(&btrace_mutex);
>> +}
>> +
>> +static inline void unlock_btrace(void)
>> +{
>> + mutex_unlock(&btrace_mutex);
>> +}
>
> Is there a reason to add these wrappers around the mutex?
>
> -- Steve
Removed on the end of the serie :-)
Thanks!
>
>> +
>> +static void get_btrace_metadata(void)
>> +{
>> + lock_btrace();
>> + btrace_metadata_count++;
>> + unlock_btrace();
>> +}
>> +
>> +static void put_btrace_metadata(void)
>> +{
>> + lock_btrace();
>> + btrace_metadata_count--;
>> + unlock_btrace();
>> +}
>> +
>> +/* events tracer */
>> +int trace_bprintk_enable;
>> +
>> +static void start_bprintk_trace(struct trace_array *tr)
>> +{
>> + get_btrace_metadata();
>> + tracing_reset_online_cpus(tr);
>> + trace_bprintk_enable = 1;
>> +}
>> +
>> +static void stop_bprintk_trace(struct trace_array *tr)
>> +{
>> + trace_bprintk_enable = 0;
>> + tracing_reset_online_cpus(tr);
>> + put_btrace_metadata();
>> +}
>> +
>> +static int init_bprintk_trace(struct trace_array *tr)
>> +{
>> + start_bprintk_trace(tr);
>> + return 0;
>> +}
>> +
>> +static struct tracer bprintk_trace __read_mostly =
>> +{
>> + .name = "events",
>> + .init = init_bprintk_trace,
>> + .reset = stop_bprintk_trace,
>> + .start = start_bprintk_trace,
>> + .stop = stop_bprintk_trace,
>> +};
>> +
>> +static __init int init_bprintk(void)
>> +{
>> + return register_tracer(&bprintk_trace);
>> +}
>> +
>> +device_initcall(init_bprintk);
>> diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
>> index 9fc8150..7897b5d 100644
>> --- a/kernel/trace/trace_output.c
>> +++ b/kernel/trace/trace_output.c
>> @@ -53,6 +53,26 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
>> return len;
>> }
>>
>> +static int
>> +trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
>> +{
>> + int len = (PAGE_SIZE - 1) - s->len;
>> + int ret;
>> +
>> + if (!len)
>> + return 0;
>> +
>> + ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
>> +
>> + /* If we can't write it all, don't bother writing anything */
>> + if (ret >= len)
>> + return 0;
>> +
>> + s->len += ret;
>> +
>> + return len;
>> +}
>> +
>> /**
>> * trace_seq_puts - trace sequence printing of simple string
>> * @s: trace sequence descriptor
>> @@ -887,6 +907,61 @@ static struct trace_event trace_print_event = {
>> .raw = trace_print_raw,
>> };
>>
>> +/* TRACE_BPRINTK */
>> +static enum print_line_t
>> +trace_bprintk_print(struct trace_iterator *iter, int flags)
>> +{
>> + struct trace_entry *entry = iter->ent;
>> + struct trace_seq *s = &iter->seq;
>> + struct bprintk_entry *field;
>> +
>> + trace_assign_type(field, entry);
>> +
>> + if (!seq_print_ip_sym(s, field->ip, flags))
>> + goto partial;
>> +
>> + if (!trace_seq_puts(s, ": "))
>> + goto partial;
>> +
>> + if (!trace_seq_bprintf(s, field->fmt, field->buf))
>> + goto partial;
>> +
>> + return TRACE_TYPE_HANDLED;
>> +
>> + partial:
>> + return TRACE_TYPE_PARTIAL_LINE;
>> +}
>> +
>> +static enum print_line_t
>> +trace_bprintk_raw(struct trace_iterator *iter, int flags)
>> +{
>> + struct trace_entry *entry = iter->ent;
>> + struct trace_seq *s = &iter->seq;
>> + struct bprintk_entry *field;
>> +
>> + trace_assign_type(field, entry);
>> +
>> + if (!trace_seq_printf(s, ": %lx : ", field->ip))
>> + goto partial;
>> +
>> + if (!trace_seq_bprintf(s, field->fmt, field->buf))
>> + goto partial;
>> +
>> + return TRACE_TYPE_HANDLED;
>> +
>> + partial:
>> + return TRACE_TYPE_PARTIAL_LINE;
>> +}
>> +
>> +static struct trace_event trace_bprintk_event = {
>> + .type = TRACE_BPRINTK,
>> + .trace = trace_bprintk_print,
>> + .latency_trace = trace_bprintk_print,
>> + .raw = trace_bprintk_raw,
>> + .hex = trace_nop_print,
>> + .binary = trace_nop_print,
>> +};
>> +
>> static struct trace_event *events[] __initdata = {
>> &trace_fn_event,
>> &trace_ctx_event,
>> @@ -895,6 +970,7 @@ static struct trace_event *events[] __initdata = {
>> &trace_stack_event,
>> &trace_user_stack_event,
>> &trace_print_event,
>> + &trace_bprintk_event,
>> NULL
>> };
>>
>> --
>> 1.6.1
>>
>>
>>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists